Chemical Equilibrium PYQs Set 3 (PDF)

Set 3 of 4 · Questions 61-90 of 94

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Mere Teacher · Previous Year Questions NEET Chemistry · Chemical Equilibrium · Set 3 (Q61-90)
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61. $Observe the following equilibrium in a 1 L flask. A (g) ⇌ B (g) At T (K), the equilibrium concentrations of A and B are 0.5 M and 0.375 M respectively. 0.1 moles of A is added into the flask and heated to T (K) to establish the equilibrium again. The new equilibrium concentrations (in M) of A and B are respectively$ (1) $0.53, 0.4 .$ (2) $0.742, 0.557 .$ (3) $0.557, 0.418 .$ (4) $0.367, 0.275 .$ 62. $Consider the following gaseous equilibria with equilibrium constants K_{1} and K_{2} respectively. SO_{2 (g)} + \frac{1}{2} O_{2 (g)} ⇌ SO_{3 (g)} 2 SO_{3 (g)} ⇌ 2 SO_{2 (g)} + O_{2 (g)} The equilibrium constants are related as$ (1) $K_{1}^{2} = \frac{1}{K _{2}}$ (2) $2 K_{1} = K_{2}^{2}$ (3) $K_{2} = \frac{2}{K _{1}^{2}}$ (4) $K_{2}^{2} = \frac{1}{K _{1}}$ 63. $1 mole of HI is heated in a closed container of capacity of 2 L . At equilibrium half a mole of HI is dissociated. The equilibrium constant of the reaction is$ (1) $0.25$ (2) $0.35$ (3) $1$ (4) $0.5$ 64. $5 moles of SO_{2} and 5 moles of O_{2} are allowed to react. At equilibrium, it was found that 60 % of SO_{2} is used up. If the partial pressure of the equilibrium mixture is one atmosphere, the partial pressure of O_{2} is$ (1) $0.52 atm$ (2) $0.21 atm$ (3) $0.41 atm$ (4) $0.82 atm$ 65. $In presence of HCl, H_{2} S results the precipitation of group-2 elements but not group-4 elements during qualitative analysis. It is due to$ (1) $higher concentration of H^{+}$ (2) $lower concentration of H^{+}$ (3) $higher concentration of S^{2 -}$ (4) $lower concentration of S^{2 -}$ 66. $The values of K_{p} / K_{c} for the following reactions at 300 K are, respectively: (At 300 K, RT = 24.62 dm^{3} atm mol^{- 1}) N_{2} (g) + O_{2} (g) ⇌ 2 NO (g) N_{2} O_{4} (g) ⇌ 2 NO_{2} (g) N_{2} (g) + 3 H_{2} (g) ⇌ 2 NH_{3} (g)$ (1) $1,24.62dm3atm mol^{- 1}, 606.0 dm^{6} atm^{2} mol^{- 2}$ (2) $1, 24.62 dm^{3} atm mol^{- 1}, 1.65\times 1 0^{- 3} dm-6atm-2mol2$ (3) $1, 4.1 \times 10^{- 2} dm^{- 3} atm^{- 1} mol, 606 dm^{6} atm^{2} mol^{- 2}$ (4) $24.62 dm^{3} atm mol^{- 1}, 606.0 dm^{6} atm^{2} mol^{- 2}, 1.65 \times 10^{- 3} dm^{- 6} atm^{- 2} mol^{2}$ 67. $At temperature T, compound AB_{2 (g)} dissociates as AB_{2 (g)} ⇌ AB_{(g)} + \frac{1}{2} B_{2 (g)} having degree of dissociation x (small compared to unity). The correct expression for x in terms of K_{p} and p is$ (1) $4 \frac{2 K _{p}}{p}$ (2) $3 \frac{2 K _{p}}{p}$ (3) $3 \frac{2 K _{p}^{2}}{p}$ (4) $K_{p}$ 68. $The effect of addition of helium gas to the following reaction in equilibrium state, is : P C I_{5} (g) ⇌ P C l_{3} (g) + C l_{2} (g)$ (1) $the equilibrium will shift in the forward direction and more of C l_{2} and P C l_{3} gases will be produced.$ (2) $the equilibrium will go backward due to suppression of dissociation of P C 1_{5} .$ (3) $helium will deactivate P C l_{5} and reaction will stop.$ (4) $addition of helium will not affect the equilibrium.$ 69. $4 moles each of SO_{2} and O_{2} gases are allowed to react to form SO_{3} in a closed vessel. At equilibrium 25 % of O_{2} is used up. The total number of moles of all the gases at equilibrium is$ (1) $6.5$ (2) $7.0$ (3) $8.0$ (4) $2.0$ 70. $4.0 moles of argon and 5.0 moles of P C I_{5} are introduced into an evacuated flask of 100 litre capacity at 610 K. The system is allowed to equilibrate. At equilibrium, the total pressure of mixture was found to be 6.0 atm. The K_{p} for the reaction is [Given : R = 0.082L atm K^{- 1} m o l^{- 1}]$ (1) $2.25$ (2) $6.24$ (3) $12.13$ (4) $15.24$ 71. $In a chemical reaction, A + 2B ⇌ K 2C+D, the initial concentration of B was 1.5 times of the concentration of A, but the equilibrium concentrations of A and B were found to be equal. The equilibrium constant (K) for the aforesaid chemical reaction is :$ (1) $16$ (2) $1$ (3) $1/4$ (4) $4$ 72. $In the Figure shown below reactant A (represented by square) is an equilibrium with product B (represented by circle). The equilibrium constant is:$ (1) $4$ (2) $8$ (3) $1$ (4) $2$ 73. $5.1 g N H_{4} SH is introduced in 3.0 L evacuated flask at 327°C. 30% of the solid N H_{4} SH decomposed to N H_{3} and H_{2} S as gases. The K_{p} of the reaction at 327°C is (R = 0.082 L atm m o l^{-1} K^{-1}, molar mass of S = 32 g m o l^{-1}, molar mass of N = 14 g m o l^{-1})$ (1) $4.9 \times 1 0^{-3} a t m^{2}$ (2) $0.242 \times 1 0^{-4} a t m^{2}$ (3) $1 \times 1 0^{-4} a t m^{2}$ (4) $0.242 a t m^{2}$ 74. $At a certain temperature in a 5 L vessel, 2 moles of carbon monoxide and 3 moles of chlorine were allowed to reach equilibrium according to the reaction, CO + C l_{2} ⇌ C O C l_{2} At equilibrium if one mole of CO is present then equilibrium constant K_{C} for reaction is$ (1) $2$ (2) $2.5$ (3) $3$ (4) $4$ 75. $For a concentrated solution of a weak electrolyte (K_{e q} =equilibrium constant) A_{2} B_{3} of concentration 'C', the degree of dissociation ' α' is$ (1) $(\frac{K _{e q}}{5 c ^{4}})^{\frac{1}{5}}$ (2) $(\frac{K _{e q}}{108 c ^{4}})^{\frac{1}{5}}$ (3) $(\frac{K _{e q}}{25 c ^{2}})^{\frac{1}{5}}$ (4) $(\frac{K _{e q}}{6 c ^{5}})^{\frac{1}{5}}$ 76. $Which of the following lines correctly show the temperature dependence of equilibrium constant, K, for an exothermic reaction$ (1) $C and D$ (2) $A and D$ (3) $A and B$ (4) $B and C$ 77. $For a reaction at equilibrium A (g) ⇌ B (g) + \frac{1}{2} C (g) the relation between dissociation constant (K), degree of dissociation (^{α}) and equilibrium pressure (p) is given by :$ (1) $K = \frac{α ^{\frac{1}{2}} p ^{\frac{3}{2}}}{( 1 + \frac{3}{2} α ) ^{\frac{1}{2}} ( 1 - α )}$ (2) $K = \frac{α ^{\frac{3}{2}} p ^{\frac{1}{2}}}{( 2 + α ) ^{\frac{1}{2}} ( 1 - α )}$ (3) $K = \frac{( α p ) ^{\frac{3}{2}}}{( 1 + \frac{3}{2} α ) ^{\frac{1}{2}} ( 1 - α )}$ (4) $K = \frac{( α p ) ^{\frac{3}{2}}}{( 1 + α ) ( 1 - α ) ^{\frac{1}{2}}}$ 78. $The relationship between K_{p} and K_{c} is K_{p} = K_{c} (R T)^{Δ n} . What would be the value of Δ n for the reaction, N H_{4} C l_{(s)} ⇌ N H_{3 (g)} + H C l_{(g)} ?$ (1) $1$ (2) $0.5$ (3) $1.5$ (4) $2$ 79. $For the reaction A_{(g)} + B_{(g)} ⇌ C_{(g)} + D_{(g)}; Δ H = - Q kJ The equilibrium constant cannot be disturbed by$ (1) $addition of A$ (2) $addition of D$ (3) $none of the above$ (4) $increasing of temperature.$ 80. $Consider the following gaseous equilibrium in a closed container of volume ' V ' at T (K) . P_{2} (g) + Q_{2} (g) ⇌ 2 PQ (g) 2 moles each of P_{2} (g), Q_{2} (g) and PQ (g) are present at equilibrium. Now one mole each of ' P_{2}' and ' Q_{2}' are added to the equilibrium keeping the temperature at T (K) . The number of moles of P_{2}, Q_{2} and PQ at the new equilibrium, respectively, are$ (1) $1.66, 1.66, 1.66$ (2) $2.56, 1.62, 2.24$ (3) $2.67, 2.67, 2.67$ (4) $1.21, 2.24, 1.56$ 81. $Consider the equilibrium CO (g) + 3 H_{2} (g) ⇌ CH_{4} (g) + H_{2} O (g) If the pressure applied over the system increases by two fold at constant temperature then (A) Concentration of reactants and products increases. (B) Equilibrium will shift in forward direction. (C) Equilibrium constant increases since concentration of products increases. (D) Equilibrium constant remains unchanged as concentration of reactants and products remain same. Choose the correct answer from the options given below :$ (1) $(A), (B) and (C) only$ (2) $(A) and (B) only$ (3) $(A), (B) and (D) only$ (4) $(B) and (C) only$ 82. $K a_{1}, K a_{2} and K a_{3} are the respective ionization constants for the following reactions (A),(B), and (C). (A) H_{2} C_{2} O_{4} H^{+} + H C_{2} O_{4}^{-} (B) H_{2} C_{2} O_{4}^{-} H^{+} + H C_{2} O_{4}^{2 -} (C) H_{2} C_{2} O_{4} 2 H^{+} + C_{2} O_{4}^{2 -} The relationship between K_{a 1}, K_{a 2} and K_{a 3} is given as$ (1) $K_{a_{3}} = K_{a_{1}} + K_{a_{2}}$ (2) $K_{a_{3}} = K_{a_{1}} - K_{a_{2}}$ (3) $K_{a_{3}} = K_{a_{1}} / K_{a_{2}}$ (4) $K_{a_{3}} = K_{a_{1}} \times K_{a_{2}}$ 83. $For the equilibrium A ⇌ B, the variation of the rate of the forward (a) and reverse (b) reaction with time is given by$ (1) (2) (3) (4) 84. $For the reaction, N_{2} O_{4} ⇌ 2 NO_{2}, graph is plotted as shown below. Identify correct statements.(A) Standard free energy change for the reaction is - 5.40 kJ mol^{- 1} .(B) As ΔG⊖ in graph is positive, N2O4 will not dissociate into NO2 at all.(C) Reverse reaction will go to completion.(D) When 1 mole of N2O4 changes into equilibrium mixture, value of Δ G^{⊖} = - 0.84 kJ mol^{- 1} (E) When 2 mole of NO2 changes into equilibrium mixture, ΔG⊖ for equilibrium mixture is - 6.24 kJ mol^{- 1} . Choose the correct answer from the options given below:$ (1) $(D) and (E) only$ (2) $(A) and (D) only$ (3) $(B) and (C) only$ (4) $(C) and (E) only$ 85. $The equilibrium Cr_{2} O_{7}^{2 -} ⇌ 2 CrO_{4}^{2 -} is shifted to the right in :$ (1) $an acidic medium$ (2) $a basic medium$ (3) $a neutral medium$ (4) $a weakly acidic medium$ 86. $At 500 K, for a reversible reaction A_{2_{(g)}} + B_{2_{(g)}} ⇌ 2 A B_{(g)} in a closed container, K_{c} = 2 \times 10^{- 5} . In the presence of catalyst, the equilibrium is attaining 10 times faster. The equilibrium constant K_{c} in the presence of catalyst at the same temperature is$ (1) $2 \times 10^{- 4}$ (2) $2 \times 10^{- 6}$ (3) $2 \times 10^{- 10}$ (4) $2 \times 10^{- 5}$ 87. $Conjugate base of H_{2} PO_{4}^{-} is$ (1) $HPO_{4}^{-}$ (2) $HPO_{4}^{2 -}$ (3) $H_{3} PO_{4}$ (4) $PO_{4}^{3 -}$ 88. $The following reaction occurs in the Blast furnance where iron ore is reduced to iron metal Fe_{2} O_{3 (s)} + 3 CO_{(g)} ⇌ Fe_{(l)} + 3 CO_{2 (g)} Using the Le-chatelier's principle, predict which one of the following will not disturb the equilibrium.$ (1) $Addition of CO_{2}$ (2) $Removal of CO_{2}$ (3) $Addition of Fe_{2} O_{3}$ (4) $Removal of CO$ 89. $An example for a neutral buffer is$ (1) $ammonium hydroxide and ammonium chloride$ (2) $acetic acid and sodium acetate$ (3) $acetic acid and ammonium hydroxide$ (4) $citric acid and sodium citrate.$ 90. $At 300 K, a gaseous reaction, A \to B + C was found to follow first order kinetics. Starting with pure A, the total pressure at the end of 20 minutes was 100 mm of Hg . The total pressure after the completion of the reaction is 180 mm of Hg . The partial pressure of A (in mm of Hg) is$ (1) $100$ (2) $90$ (3) $180$ (4) $80$